Five bottle bombs were found in South Jeffco on Jan. 2 and 3, the Sheriff’s Office reported.

Four of the bombs, also referred to as “overpressure devices,” were discovered Friday at Easton Park off West Coal Mine Avenue, near Dakota Ridge High School, by Jeffco parks employees. All four of the bombs at Easton had been detonated.

The fifth bomb was discovered in the parking lot between The Edge Ice Arena and The Ridge Recreation Center on Thursday, Jan. 2. That bomb was inert, said sheriff’s spokesman Mark Techmeyer.

“An overpressure device is … when there’s so much pressure inside a container, it will burst and explode with great force. Some of them are made out of plastic,” said Deputy Mark Miller, a member of the sheriff’s bomb squad. “They’re very dangerous for the public and everyone in the surrounding area.”

One of the devices found in Easton had been made from glass, while the other four were made from various-sized plastic bottles.

There are no suspects and apparently no clues indicating who might have made the bombs.

Miller said even devices made out of plastic bottles can cause serious injuries.

“They’re very powerful. Statistically, you could lose a limb. A 2-liter soda bottle, you could lose a hand,” Miller said.

Miller said the devices can be made easily and at little cost using instructions found on the Internet.

Part of the danger comes from how unstable the bombs are once they're made, Miller said.

“It has no fuse. That's part of the problem. You don’t know when or how it’s going to go off. It’s a timing thing. It has to do with the chemicals mixed into it and the air temperature,” Miller said. “It sounds like a science project, but they’re dangerous.”

In one case a few years ago, Miller said, a Jeffco homeowner found a device and put it in the garbage. As the temperature changed, the device exploded in the garbage can.

Manufacturing the devices was recently classified as a felony by the state legislature, and the Sheriff’s Office takes them very seriously, Miller said.

The Sheriff’s Office is warning people not to pick up any suspicious items they encounter but instead to call its tip line at 303-277-0211.

Check back at www.columbinecourier.com and follow Ramsey Scott on Twitter @RamseyColumbine for more information as it becomes available.